Process and intermediate compounds for preparation of pesticidal fluoroolefin compounds

ABSTRACT

A two-step process for the preparation of fluoroolefin compounds of formula I  
                 
 
     wherein  
     R is hydrogen or alkyl, and R 1  is alkyl or cyclopropyl, or R and R 1  are taken together with the carbon atom to which they are attached to form a cyclopropyl group;  
     Ar is phenyl or naphthyl both of which are optionally substituted;  
     Ar 1  is phenoxyphenyl, biphenyl, phenyl, benzylphenyl, or benzoylphenyl, all of which may be optionally substituted,  
     comprising reacting fluorobromoolefin compounds of formula II  
                 
 
     with organozinc compounds of formula III or IV 
     BrZnCH 2 Ar 1   III 
     Zn(CH 2 Ar 1 ) 2   IV 
     in the presence of a palladium catalyst and a solvent,  
     which compounds of formula II are obtained by reacting aldehyde compounds of formula V  
                 
 
     with  
     (a) fluorotribromomethane,  
     (b) a tri(substituted)phosphine or a hexaalkylphosphoramide or a mixture thereof, and  
     (c) zinc,  
     in the presence of a solvent,  
     compounds of formula II.

[0001] The present invention provides a two-step process for thepreparation of pesticidal fluoroolefin compounds of formula I

[0002] wherein

[0003] R is hydrogen or C₁-C₄-alkyl, and

[0004] R¹ is C₁-C₄-alkyl or cyclopropyl, or

[0005] R and R¹ are taken together with the carbon atom to which theyare attached to form a cyclopropyl group;

[0006] Ar is phenyl which is unsubstituted or substituted with anycombination of from one to three halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups, or

[0007] 1- or 2-naphthyl which is unsubstituted or substituted with anycombination of from one to three halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups;

[0008] Ar¹ is phenoxyphenyl which is unsubstituted or substituted withany combination of from one to five halogen, C₁-C₄-alkyl,C₁-C₄-haloalkyl, C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups,

[0009] biphenyl which is unsubstituted or substituted with anycombination of from one to five halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups,

[0010] phenyl which is unsubstituted or substituted with any combinationof from one to five halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl, C₁-C₄-alkoxyor C₁-C₄-haloalkoxy groups,

[0011] benzylphenyl which is unsubstituted or substituted with anycombination of from one to five halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups, or

[0012] benzoylphenyl which is unsubstituted or substituted with anycombination of from one to five halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups,

[0013] which comprises reacting fluorobromoolefin compounds of formulaII

[0014] wherein Ar, R and R¹ are as described above, with organozinccompounds of formula III or IV

BrZnCH₂Ar¹  III

Zn(CH₂Ar¹)₂  IV

[0015] wherein Ar¹ is as described above, in the presence of a palladiumcatalyst and a solvent,

[0016] which compounds of formula II are obtained by reacting aldehydecompounds of formula V

[0017] wherein Ar, R and R¹ are as defined above, with

[0018] (a) fluorotribromomethane,

[0019] (b) a tri(substituted)phosphine or a hexaalkylphosphoramide or amixture thereof, and

[0020] (c) zinc,

[0021] in the presence of a solvent.

[0022] In compounds of formula I, the configuration of the groupsArCRR¹— and —CH₂Ar¹ about the double bond is preferably predominatelymutually trans. “Predominately trans” means that the trans-compound ispresent at a percentage of at least 80%, preferably above 95%.

[0023] The present invention also relates to the fluorobromoolefincompounds of formula II.

[0024] Pesticidal fluoroolefin compounds and processes for theirpreparation are described in WO 94/06741 and GB-A 2 288 803.

[0025] However, those processes are not entirely statisfactory becausethe fluoroolefin compounds are produced in relatively low yields frommulti-step processes.

[0026] It was therefore an object of the present invention to provide animproved process for the preparation of fluoroolefin compounds.

[0027] Accordingly, a two-step overall process for the preparation offluoroolefin compounds of formula I starting form aldehyde compounds offormula V, via intermediate compounds of formula II, has been found.

[0028] Furthermore, compounds of formula II have been found.

[0029] Advantageously, the inventive process affords compounds offormula I which are predominately in the trans-configuration.

[0030] WO 94/06741 and GB-A 2 288 803 disclose that fluoroolefincompounds are obtained in four steps starting from aldehyde compounds offormula V.

[0031] Exemplary of halogen hereinabove are fluorine, chlorine, bromineand iodine;

[0032] The term “alkyl” is defined as a saturated, straight or branchedchain hydrocarbon with 1 to 4 carbon atoms, such as methyl, ethyl,propyl, 1-methyl-ethyl, butyl, 1-methyl-propyl, 2-methyl-propyl and1,1-dimethyl-propyl.

[0033] The term “alkoxy” is defined an a saturated, straight or branchedchain hydrocarbon with 1 to 4 carbon atoms (as described above) which isbond to the backbone via an oxygen (—O—) atom;

[0034] The term “haloalkyl” is defined as an alkyl group, as definedabove, wherein the hydrogen atoms may be partially or totallysubstituted with halogen atoms as defined above, wherein the halogenatoms may be the same or different, for example C₁-C₂-haloalkyl such aschloro-methyl, bromomethyl, dichloro-methyl, trichloro-methyl,fluoro-methyl, difluoro-methyl, trifluoro-methyl, chloro-fluoro-methyl,dichlorofluoro-methyl, chloro-difluoro-methyl, 1-chloro-ethyl,1-bromo-ethyl, 1-fluoro-ethyl, 2-fluoro-ethyl, 2,2-difluoro-ethyl,2,2,2-trifluoro-ethyl, 2-chloro-2-fluoro-ethyl,2-chloro-2,2-difluoro-ethyl, 2,2-dichloro-2-fluoro-ethyl,2,2,2-trichloro-ethyl and pentafluoro-ethyl, wherein the halogen atomsmay be the same or different.

[0035] The term “haloalkoxy” is defined as an alkoxy group as definedabove, wherein the hydrogen atoms may be partially or totallysubstituted with one or more halogen atoms as defined above, wherein thehalogen atoms may be the same or different.

[0036] Wavy lines in structural formulae depict the carbon-carbon doublebond in both the E- or the Z-isomeric configuration.

[0037] Groups containing two or more rings, such as phenoxyphenyl,biphenyl, benzylphenyl and benzoylphenyl, which may be substituted, maybe substituted on either ring unless otherwise specified herein.

[0038] In a preferred embodiment of the present invention, afluorobromoolefin of formula II is reacted with at least one molarequivalent, such as 1 to 2 molar equivalents, of an organozinc compoundof formula III or IV, and 0.001 to 0.2, preferably 0.01 to 0.1 molarequivalent of a palladium catalyst in the presence of a solvent,preferably in a temperature range of −70° C. to 70° C.

[0039] The product compounds of formula I may be isolated by dilutingthe reaction mixture with water and extracting the product with asuitable extraction solvent. In the isolation procedure, conventionalextraction solvents such as ether, ethyl acetate, toluene, anddichloromethane may be utilized.

[0040] Preferred palladium catalysts for use in the present inventioninclude, but are not limited to, bis(dibenzylideneacetone)palladium(0),tetrakis(triphenylphosphine)palladium(0), bis(acetonitrile)palladium(II)chloride, bis(triphenylphosphine)palladium(II) chloride,[1,4-bis(diphenylphosphine)butane]palladium(II) dichloride,[1,1′-bis(diphenylphosphino)ferrocene]palladium(II) diacetate,palladium(II) acetate, palladium(II) chloride and mixtures thereof.

[0041] Preferred solvents for use in the preparation of compounds offormula I include, but are not limited to, aromatic hydrocarbons such astoluene, benzene, xylenes and mesitylene, halogenated aromatichydrocarbons such as chlorobenzene and fluorobenzene, carboxylic acidamides, such as N,N-dimethylformamide, ethers such as tetrahydrofuranand dioxane, and halogenated hydrocarbons such as chloroform and carbontetrachloride, and mixtures thereof.

[0042] Preferred solvents for use in the preparation of compounds offormula I include carboxylic acid amides and ethers and mixturesthereof, preferably N,N-dimethylformamide and tetrahydrofuran andmixtures thereof.

[0043] In a preferred embodiment of the present invention for thepreparation of fluorobromoolefin compounds of formula II, aldehydecompounds of formula V are reacted with at least one molar equivalent,such as 2 to 6 molar equivalents, of fluorotribromomethane, and at leastone molar equivalent, such as 2 to 7 molar equivalents, of atri(substituted)phosphine, and at least one molar equivalent, such as 1to 4 molar equivalents, of zinc, preferably zinc dust, in the presenceof a solvent, preferably in a temperature range of −20° C. to 70° C.

[0044] Preferred tri(substituted)phosphines for use in this inventioninclude, but are not limited to, triaryl-phosphines such astriphenylphosphine or tri-p-tolyl-phosphine, and tri(branchedC₃-C₆-alkyl)-phosphines such as triisopropylphosphine ortritertiarybutylphosphine, and mixtures thereof.

[0045] Preferred tri(substituted)phosphines which produce compounds offormula II with a preferred ratio of (E):(Z)-isomer includetriisopropylphosphine and tritertiarybutylphosphine. Preferred ratios of(E):(Z)-isomer of formula II are ratios above 1.5:1, preferably above2.5:1, more preferably above 3.5:1 (E):(Z).

[0046] Preferred hexaalkylphosphoramides for use in the presentinvention include hexamethylphosphoramide or hexaethylphosphoramide, andmixtures thereof.

[0047] Preferred solvents for use in the preparation offluorobromoolefins of formula II include, but are not limited to, etherssuch as diethyl ether or tetrahydrofuran and halogenated hydrocarbonssuch as dichloromethane, and mixtures thereof.

[0048] More preferred solvents for use in the preparation offluorobromoolefins of formula II include diethyl ether, tetrahydrofuranand dichloromethane, and mixtures thereof.

[0049] Starting organozinc compounds of formulae III and IV may beprepared by reacting a bromide compound of formula VI

BrCH₂Ar¹  VI

[0050] wherein Ar¹ is described above, with activated zinc (e.g., Riekezinc) in the presence of a solvent such as tetrahydrofuran.

[0051] Aldehyde compounds of formula V may be prepared usingconventional procedures known in the art, see for example: Bioorg. Med.Chem. Lett. (1998), 8(3), p. 301; Chem. Pharm. Bull. (1996), 44(10), p.1858; Tetrahedron Lett. (1996), 37(5), 2629; J. Org. Chem. Soc. (1995),60 (18), p. 5803; and J. Am. Chem. Soc. (1993), 115, p. 3030.

[0052] Preferred fluoroolefin compounds of formula I which may beprepared by the process of the present invention are those wherein thevariables have the following meanings, each alone or in combination:

[0053] Preferred are compounds of formula I wherein R is hydrogen and R¹is isopropyl or cyclopropyl;

[0054] Also preferred are compounds of formula I wherein R and R¹ aremethyl;

[0055] Furthermore, preferred are compounds of formula I wherein R andR¹ are taken together with the carbon atom to which they are attached toform a cyclopropyl group.

[0056] Preferred are compounds of formula I wherein Ar is phenyl whichis unsubstituted or substituted with any combination of from one tothree halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl, C₁-C₄-alkoxy orC₁-C₄-haloalkoxy groups.

[0057] More preferred are compounds of formula I wherein Ar is phenylwhich is unsubstituted or substituted with any combination of from oneto three halogen, preferably chlorine of fluorine.

[0058] Most preferred are compounds of formula I wherein Ar is4-chlorophenyl.

[0059] Moreover, compounds of formula I are preferred wherein Ar¹ is

[0060] 3-phenoxyphenyl which is unsubstituted or substituted with anycombination of from one to five halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups,

[0061] 3-biphenyl which is unsubstituted or substituted with anycombination of from one to five halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups, or

[0062] phenyl which is unsubstituted or substituted with any combinationof from one to five halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl, C₁-C₄-alkoxyor C₁-C₄-haloalkoxy groups.

[0063] More preferred are compounds of formula I wherein Ar¹ is3-phenoxy-phenyl which is unsubstituted or substituted with anycombination of from one to five halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups.

[0064] Especially preferred are compounds of formula I wherein Ar¹ is3-phenoxyphenyl which is unsubstituted or substituted with anycombination of from one to six halogen, preferably fluorine.

[0065] Most preferred compounds of formula I agents are those wherein

[0066] R is hydrogen and R¹ is isopropyl or cyclopropyl, or R and R¹ aremethyl, or R and R¹ are taken together with the carbon atom to whichthey are attached to form a cyclopropyl group; and

[0067] Ar is phenyl which is unsubstituted or substituted with anycombination of from one to three halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups; and

[0068] Ar¹ is 3-phenoxyphenyl which is unsubstituted or substituted withany combination of from one to five halogen, C_(l)-C₄-alkyl,C₁-C₄-haloalkyl, C₁-C₄-alkoxy or C₁-C₄-haloalkoxy, groups.

[0069] Preferred fluorobromoolefin compounds of formula II are thosewherein R, R¹ and Ar are as defined above for preferred compounds offormula I.

[0070] In a preferred embodiment of this invention, compounds of formulaII are in the (E)-configuration.

[0071] Preferred compounds of formulae III, IV and V for use in theinventive process are those wherein the variables Ar, R, and R¹,respectively, are as defined above for preferred compounds of formula I.

EXAMPLE 1 Preparation of(Z)-1-(p-Tolyl)-1-[2-fluoro-3-(3-phenoxyphenyl)-1-propenyl]cyclopropane,

[0072]

[0073] Under a nitrogen atmosphere, a mixture of1-(2-bromo-2-fluoroethene)-1-(p-tolyl)cyclopropane, (E)- to (Z)-ratio5:3 (0.5 g, 2 mmol), tetrakis(triphenylphosphine)-palladium(0) (0.2 g,0.2 mmol), and tetrahydrofuran (20 ml) was treated with a3-phenoxybenzylzinc bromide solution (prepared from3-phenoxybenzylbromide (1.1 g, 4 mmol) and Rieke zinc (3.25 ml of a 1.5molar solution in tetrahydrofuran), and tetrahydrofuran 20 ml). Theresultant reaction mixture was stirred at room temperature until thereaction was complete as followed by gas chromatography analysis,diluted with water, and extracted with ethyl acetate. The organicextract was dried over anhydrous magnesium sulfate, and concentrated invacuo to obtain a residue. Column chromatography of the residue usingsilica gel and heptane gave the title product (0,18 g) predominately inthe (Z)-configuration.

[0074] Using essentially the same procedure, the following compounds areobtained predominately in the (Z)-configuration:

Ar R R¹ Ar¹

—CH₂—CH₂—

CH₃ CH₃

—CH₂—CH₂—

CH₃ CH₃

CH(CH₃)₂ H

CH₃ CH₃

EXAMPLE 2 Preparation of(Z)-4-(p-Chlorophenyl)-2-fluoro-5-methyl-1-(3-phenoxyphenyl)-2-hexene,

[0075]

[0076] Under a nitrogen atmosphere, a mixture of1-bromo-3-(p-chlorophenyl)-1-fluoro-4-methyl-1-pentene, (E)- and (Z)-(0.9 g, 3.1 mmol), tetrakis(triphenylphosphine)-palladium(0) (0.25 g,0.22 mmol), and N,N-dimethyl-formamide (20 ml) was treated with 5 ml ofa 3-phenoxybenzylzinc bromide solution (prepared from 3-phenoxybenzylbromide (1.3 g, 5.4 mmol) and Rieke zinc (4 ml of a 1.5 molar solutionin tetrahydrofuran), and tetrahydrofuran 20 ml) The resultant reactionmixture was stirred at room temperature for one hour, treated with anadditional 5 ml of the 3-phenoxybenzylzinc bromide solution, stirred atroom temperature, and poured into 2 N hydrochloric acid solution. Theresultant aqueous mixture was extracted with diethyl ether. The organicextract was dried over anhydrous magnesium sulfate, and concentrated invacuo to obtain a residue. Column chromatography of the residue usingsilica gel, and 100:1 and 200:1 hexane/ethyl acetate solutions gave thetitle product (0.35 g) predominately in the (Z)-configuration.

[0077] Following essentially the same procedure, but using theappropriate palladium catalyst, the following compounds are obtainedpredominately in the (Z)-configuration:

Pd Catalyst Ar R R¹ Ar¹ Pd[P(C₆H₅)₃]₄

CH₃ CH₃

(CH₃CN)₂PdCl₂

—CH₂—CH₂—

(CH₃CN)₂PdCl₂

—CH₂—CH₂—

EXAMPLE 3 Preparation of (E)- and(Z)-1-(2-Bromo-2-fluoroethene)-1-(p-chlorophenyl)cyclopropane,

[0078]

[0079] A mixture of 1-carboxaldehyde-1-(p-chlorophenyl)-cyclopropane(0.2 g, 1.1 mmol), fluorotribromomethane (0.39 ml, 1.08 g, 4.0 mmol),zinc dust (0.12 g, 1.8 mmol), triisopropylphosphine (0.75 ml, 3.9 mmol),and diethyl ether (20 ml) was stirred at room temperature for one hour,treated with additional triisopropylphosphine (0.3 ml, 1.6 mmol) to givethe title product having an (E)- to (Z)-isomer ratio of 4:1. Thisreaction is listed as no. 1 in Table I.

[0080] Following essentially the same procedure, but varying thephosphine and solvent,1-(2-bromo-2-fluoroethene)-1-(p-chlorophenyl)cyclopropane, (E)- and (Z)-is obtained in the ratios shown below in Table I.

[0081] As can be seen from the data in Table I, the (E)-isomer of1-(2-fluoroethene)-1-(p-chlorophenyl)cyclopropane is obtained insignificantly greater amounts relative to the (Z)-isomer when thephosphine is triisopropylphosphine or tritertiarybutylphosphine. TABLE I

Product Ratio Reaction No. Phosphine Solvent (E:Z) 1 [CH(CH₃)₂]₃Pdiethyl ether 4:1 2 [(CH₂)₃CH₃]₃P diethyl ether No Reaction 3 (C₆H₅)₃Pdiethyl ether No Reaction 4 [CH(CH₃)₂]₃P dichloromethane 1,7:1 5[C(CH₃)₃]₃P dichloromethane 2:1 6 (C₂H₅)₃P dichloromethane No Reaction 7(CH₃)₃P dichloromethane No Reaction 8 (C₆H₅)₃P dichloromethane 1:1.4 9[CH(CH₃)₂]₃P tetrahydrofuran 2,5:1 10 [(CH₂)₃CH₃]₃P tetrahydrofuran NoReaction 11 (CH₃)₃P tetrahydrofuran No Reaction 12 (C₆H₅)₃Ptetrahydrofuran 1:1

EXAMPLE 4 Preparation of (E)- and(Z)-1-(2-Bromo-2-fluoroethene)-1-(p-tolyl)cyclopropane,

[0082]

[0083] Following essentially the same procedure as described in Example3, but using the reactants shown above, the title product is obtainedhaving an (E)- to (Z)-isomer ratio of 3.6:1.

EXAMPLE 5

[0084] Following essentially the same procedure as described in Example3, the following compounds are obtained:

Product Ratio W R R¹ Phosphine Solvent (E:Z) Cl CH(CH₃)₂ H (C₆H₅)₃Pdichloro- 2:1 methane F CH₃ CH₃ (C₆H₅)₃P tetra- 2:1 hydrofuran F—CH₂—CH₂— (C₆H₅)₃P tetra- 1:1 hydrofuran Cl CH₃ CH₃ (C₆H₅)₃P dichloro-1:1,3 methane

1. A two-step process for the preparation of fluoroolefin compounds offormula I

wherein R is hydrogen or C₁-C₄-alkyl, and R¹ is C₁-C₄-alkyl orcyclopropyl, or R and R¹ are taken together with the carbon atom towhich they are attached to form a cyclopropyl group; Ar is phenyl whichis unsubstituted or substituted with any combination of from one tothree halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl, C₁-C₄-alkoxy orC₁-C₄-haloalkoxy groups, or 1- or 2-naphthyl which is unsubstituted orsubstituted with any combination of from one to three halogen,C₁-C₄-alkyl, C₁-C₄-haloalkyl, C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups;Ar¹ is phenoxyphenyl which is unsubstituted or substituted with anycombination of from one to five halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups, biphenyl which is unsubstitutedor substituted with any combination of from one to five halogen,C₁-C₄-alkyl, C₁-C₄-haloalkyl, C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups,phenyl which is unsubstituted or substituted with any combination offrom one to five halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl, C₁-C₄-alkoxy orC₁-C₄-haloalkoxy groups, benzylphenyl which is unsubstituted orsubstituted with any combination of from one to five halogen,C₁-C₄-alkyl, C₁-C₄-haloalkyl, C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups,or benzoylphenyl which is unsubstituted or substituted with anycombination of from one to five halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups, which comprises reactingfluorobromoolefin compounds of formula II

wherein Ar, R and R¹ are as described above, with organozinc compoundsof formula III or IV BrZnCH₂Ar¹  IIIZn(CH₂Ar¹)₂  IV wherein Ar¹ is asdescribed above, in the presence of a palladium catalyst and a solvent,which compounds of formula II are obtained by reacting aldehydecompounds of formula V

wherein Ar, R and R¹ are as defined above, with (a)fluorotribromomethane, (b) a tri(substituted)phosphine or ahexaalkylphosphoramide or a mixture thereof, and (c) zinc, in thepresence of a solvent.
 2. The process according to claim 1 wherein thepalladium catalyst is selected from the group consisting ofbis(dibenzylideneacetone)palladium(0),tetrakis(triphenylphosphine)palladium(0), bis(acetonitrile)palladium(II)chloride, bis(triphenylphosphine)palladium(II) chloride,[1,4-bis(diphenylphosphine)butane]palladium(II) dichloride,[1,1′-bis(diphenylphosphino)ferrocene]palladium(II) diacetate,palladium(II) acetate and palladium(II) chloride, and mixtures thereof.3. The process according to claims 1 or 2 wherein the palladium catalystis present in an amount of 0.001 to 0.2 molar equivalent relative to thecompound of formula II.
 4. The process according to claims 1 to 3wherein the phosphine is selected from the group consisting oftriphenylphosphine, tri-(p-tolyl)phosphine and a tri-(branchedC₃-C₆-alkyl)phosphine and mixtures thereof; and thehexaalkylphosphoramide is selected from the group consisting ofhexamethylphosphoramide and hexaethylphosphoramide and mixtures thereof.5. The process according to claims 1 to 4 wherein fluorotribromomethaneis present at 2 to 6 molar equivalents related to compounds of formulaV.
 6. The process according to claims 1 to 5 wherein thetri(substituted)phosphine is present at 2 to 7 molar equivalents relatedto compounds of formula V.
 7. The process according to claims 1 to 6wherein zinc is present at 1 to 4 molar equivalents related to compoundsof formula V.
 8. The process according to claims 1 to 7 wherein R ishydrogen and R¹ is isopropyl or cyclopropyl, or R and R¹ are methyl, orR and R¹ are taken together with the carbon atom to which they areattached to form a cyclopropyl group; Ar is phenyl which isunsubstituted or substituted with any combination of from one to threehalogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl, C₁-C₄-alkoxy or C₁-C₄-haloalkoxygroups; and Ar¹ is 3-phenoxyphenyl which is unsubstituted or substitutedwith any combination of from one to five halogen, C₁-C₄-alkyl,C₁-C₄-haloalkyl, C₁-C₄-alkoxy or C₁-C₄-haloalkoxy groups.
 9. A compoundof formula II according to claim 1 wherein R, R¹ and Ar are as definedin claims 1 or
 8. 10. A compound of formula II according to claim 9wherein the compound is in the (E)-configuration.